The current-voltage relationship of salamander depolarizing bipolar cells displays a strong outward rectification. As a result of this membrane nonlinearity, increases in the intensity of bright lights cause relatively smaller amplitude increases in the voltage than in the current responses and the latter have a proportionally smaller after effect. The light-evoked responses appear to consist of at least two components: a chloride-- dependent on-off increase in membrane conductance and a faster depolarizing input that is lost through diffussional exchange between the cytosol and the content of patch pipettes. Because of its on-off pattern, the chloride-dependent component is thought to reflect input from amacrine or interplexiform cells.